Hello.
Bartlomiej Zolnierkiewicz wrote:
[PATCH] ide: don't allow DMA to be enabled if CONFIG_IDEDMA_{ICS,PCI}_AUTO=n
For CONFIG_IDEDMA_{ICS,PCI}_AUTO=n and/or "ide=nodma" option the host/device
Not only that: it also would affect CompactFlash with no DMA support but
with DMA autotuning enabled in IDE core...
are not programmed for DMA and it is also explicitly disabled by ide_set_dma()
(->ide_dma_check returns "-1"). However the code responsible for manually
enabling DMA ("hdparm -d 1") has a bug which results in DMA being erroneously
enabled - ide_set_dma() incorrectly passes "0" return value to set_using_dma().
Heh, I've just run into this myself while trying to retro-fit Palmchip
BK3710 IDE driver into 2.6.18 properly.
This may work if BIOS/firmware configured the host/device for DMA and chipset
allows independent configuration of DMA/PIO modes but won't work after suspend
and is generally unsafe on many chipsets (possibly including data corruption
if the same registers are used for DMA/PIO timings).
Timeouts ensued in my case...
WBR, Sergei
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